It is well-known that phtalocyaninic pigments, in particular those based on copper phtalocyanine, in the metastable forms named .alpha.,.gamma.,.delta.,.epsilon., present in the drawback of being crystallizing in the presence of solvents, particularly aromatic solvents, and that, moreover, the above cited metastable forms have the tendency to convert to the stable form .beta., a phenomenon that is accompanied by a change in tone, by an increase in the particle size of the pigment resulting in the attendant disadvantage of a considerable decrease in dyeing power.
The crystals of the .beta. form, in their turn under the action of heat or of the crystallization solvents, tend to grow, with consequent loss of dyeing power, modification of the pigmentary properties and increase of the viscosity of the medium into which they are incorporated.
A further serious drawback of such phtalocyaninic pigments, in particular of those metallized with copper, is their tendency to flocculate, with consequent poor dripping properties of the corresponding dispersions, or separation or settling of the pigment from varnishes containing two or more pigments, in particular from non-aqueous dispersion systems of a weak viscosity such as those for varnishes and inks.